Locking closure for a container and blank therefor



LOCKING CLOSURE FOR A CONTAINER AND BLANK THEREFOR 2 Sheets-Sheet 1Filed Aug. 11. 1965 INVENTOR 7 QObEF-YT L. WALDROP ATTORNEY- R; L.WALVDROP Jan. 2, 1968 LOCKING CLOSURE FOR A CONTAINER AND BLANK THEREFORFiled Aug. 11, 1965 2 Sheets-Sheet ,2

. INVENTOR ROBERT L. WALDROP ATTORNEY5 United States Patent C) 3,361,327LOCKING CLOSURE FOR A CONTAINER AND BLANK THEREFOR Robert L. Waldrop,Bon Air, Va., assignor to Reynolds Metals Company, Richmond, Va., acorporation of Delaware Filed Aug. 11, 1965, Ser. No. 478,835 13 Claims.(Cl. 229-38) ABSTRACT OF THE DISCLOSURE This disclosure relates to alocking top closure for a container wherein such top closure is formedby folding extension flaps provided in adjoining vertical walls inwardlyand substantially into a common plane. The locking closure has an outerflap which is folded and locked in position last and such lockingclosure is foolproof in that irrespective of the sequence used infolding the inner extension flaps in position a positive locking closureis always provided.

This invention pertains to an improved container closure and moreparticularly to a foolproof container locking closure and to an improvedblank for making such container closure or the like.

Many of the containers, such as food containers, in current use, areopened to obtain access to the product carried therein by opening anexterior wall, such as the entire top thereof, and then reclosed toprotect any remaining product. Such current containers generally arediflicult to re-close positively, while others have expensively producedclosures, and still others will only provide closure by followingprocedures usually too inconvenient to be followed.

Accordingly, it is a feature of this invention to provide a closure fora container which is inexpensively and efiiciently produced withoutrequiring special machinery.

Another feature of this invention is to provide means for easily openinga container by tearing away a portion of an exterior wall thereof whileproviding a positive closure for such exterior wall which is closable ina foolproof manner.

Another feature of this invention is to provide a foolproof lockingclosure for a container having an open top wherein the top is formed bycooperating extension flaps in a plurality of oppositely arranged sideWalls forming such container and one of said extension flaps is definedas an outer flap provided with suitable projections therein andidentification means on the outer side thereof, the projections assuringthat it will intermesh with the remaining flaps to form said top whilethe identification means assuring it is the final flap to be closed.

Another feature of this invention is to provide score means in suchouter flap to thereby provide greater flexibility therefor, and toassure easier cooperation with the extension flap means.

Therefore, it is an object of this invention to provide an improvedcontainer having one or more of the novel features of this invention asset forth above or hereinafter shown or described.

Another object of this invention is to provide an improved containerblank for such a container or the like.

Other objects, uses, and advantages of this invention are apparent froma reading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIGURE 1 is a perspective view illustrating a container having thefoolproof locking closure of this in- 3,361,327 Patented Jan. 2, 1968vention and showing a sealing flap holding such container sealed priorto its initial opening.

FIGURE 2 is a perspective view of the upper portion of such containerwith the extension flaps forming the top thereof extended vertically andwith the sealing flap torn away and held immediately above its tearline.

FIGURE 3 is a perspective View of the upper portion of such containershowing the first step in one of the several possible foolproof ways ofsequentially closing the extension flaps forming the top wall andillustrating the closure of a side wall flap first prior to closing theend wall flaps.

FIGURE 4 is a perspective view of the upper portion of such containerillustrating the second step in which the end flaps are foldedoverlapping the side wall flap and showing the outer flap in itsvertical position.

FIGURE 5 is a perspective view of the upper portion of such containershowing the third step in which the outer extension flap is beinginserted into centrally located elongated slit means defined by theother extension flaps in their folded positions.

FIGURE 6 is a perspective view of the upper portion of such containershowing the outer flap in its closed position and the top of thecontainer positively reclosed.

FIGURE 7 is a plan view of an improved container blank used to make thecontainer of FIGURE 1 particularly showing the foolproof locking closureof this invention and showing the center portion of such blank brokenaway.

While the various features of this invention are hereinafter illustratedand described as being particularly adaptable for providing a reclosurefor the top wall of a food container, it is to be understood that thevarious features of this invention can be utilized singly or in anycombination thereof to provide foolproof reclosures for other walls andfor any variety of articles that may be carried within such container.

Therefore, this invention is not to be limited to only the embodimentsillustrated in the drawings because the drawings are merely utilized toillustrate one of the Wide variety of uses of this invention.

In the exemplary embodiment of the invention illustrated in FIGURE 1, acontainer 20 is provided having a sealed top which utilizes thefoolproof locking closure of this invention.

Container 20 is initially opened, in this example, by tearing away anintegral sealing strip in the top thereof permitting extension flaps inthe vertical walls and forming such top to be folded outwardly foraccess to the food product therein. Container 20 may then be reclosedeasily in a foolproof manner in that irrespective of the order offolding such extension flaps inwardly to form the container top theclosure of this invention provides positive locking therefor.

Container 20 has side wall means shown as a plurality of six foldablyconnected Walls 21, 22, 23, 24, 25 and 26 which are preferably made froma single sheet of foldable material. Walls 21, 22, 23 and 24 haveextension flap means extending therefrom and cooperating together toclose the top of said container 20, illustrated as top wall 26.

An extension flap 34B and 31 extends from oppositely arranged end walls21 and 22 respectively, while an extension flap 32 extends from firstside wall 23 and extension flap 33 extends from oppositely arrangedsecond side wall 24.

Each end wall extension flap 30 and 31 has its base defined by a scoreline 34 and 35 respectively at the top edge of associated walls 21 and22, and the extension flap is the same width as its associated end wall.

The area of extension flap 30 is defined by a rectangular portion 33Aand a right triangular portion 30B, each portion 30A and 3tlB lying withone of their sides along the base of extension flap 30, Le, along scoreline 34, and another of their sides adjoining on a common line. Righttriangular portion 30B has its hypotenuse extending between one terminalend of the extension flap base and a point illustrated at 33 along theadjoining side common to right triangular portion 30B and rectangularportion 30A. Point 38 is generally along the middle portion of that sideof area 30A which forms a part of the adjoining side. 7 Similarly thearea of extension flap 31 is defined by a rectangular portion 31A and aright triangular portion 31B each lying with one of their sides alongthe base of flap 31 and another of their sides adjoining. Righttriangular pOrtion 31B has its hypotenuse extending between the terminalend of its extension flap base, opposite a corresponding end in fiap 30,and a point illustrated at 39 along the adjoining side common toportions 31A and 31B.

The terminal end areas of each flap 30 and 31 extending outwardly beyondpoints 38 and 39 are generally rectangular in shape and provide supportfor outer flap 33.

Extension flap 32 in side wall 23 has its base defined by a score line36 at the upper end of wall 23 and is generally coextensive in widthwith the width of side wall 23. Flap 32 has a generally rectangularcut-out illustrated at 37 at its terminal end and defined by U-shapedcut 58 in such flap.

It will be seen in FIGURES 3-6 that extension flaps 30, 31, and 32 areadapted for folding inwardly to define a centrally located elongatedslit means or slot 40 in the container. The length of slot 49 is definedby the Width of the central portion of U-shaped out line 58.Furthermore, it will be apparent from the drawings that the length orextension of flap 32 from its base to its central outer edge as definedby the center portion of cut 58 is smaller than the height of eachtriangular portion normal to its respective adjoining side. Thisdimensioning defines the width of slot 40.

Extension flap 33 in side wall 24 is of generally rectangularconfiguration, and has its base defined by a score line 41 at the upperend of wall 24 while being generally coextensive in width with side Wall24. Flap 33 has cut means or slits 42 defining a generally rectangulartear-off portion 43, used in this example as a sealing flap, coextensivewith flap 33 and having a generally centrally located trapezoidalcut-out in one side thereof shown at 44. The wider parallel side of thetrapezoidal cut-out in flap 33 coincides with the tear edge defined byslit portions 42A and 42B of slit means 42, such that upon tearing ofifsealing flap 43 a centrally located trapezoidal extension 45 is providedat the terminal end of the rectangular outer extension flap 33.

It will be seen therefore that the remaining area of flap 33 is definedby a generally trapezoidal portion 46 (see FIGURE 7 showing thecontainer blank) flanked at either side by a pair of right triangulartab portions 47 and 48. Tab portions 47 and 48 are of equal height whichis less than the height of trapezoidal portion 46 such that trapezoidalextension 45 extends outwardly beyond tabs 47 and 48.

Tab portions 47 and 48 are defined by symmetrically arranged score meansor lines 47A and 48A respectively in outer fiap 33.

Score lines 47A and 48A are defined by extending each nonparallel sideof the trapezoidal extension 45 inwardly to the end of the outerextension flap base (score line 41) adjacent thereto. Score lines 47Aand 48A provide greater flexibility for the outer flap 33 duringinsertion of the trapezoidal extension 45 in slot 40.

To assure that flap 33 is folded last upon closing top 26,identification means, such as color coding, writing, or application ofmetal foil or the like is placed on the outer surface of flap 33. A userwill realize immediately that flap 33 is the last one to be foldedinwardly.

FIGURES 36 illustrate the various steps in one of the possible ways offolding extension flaps 30-33 to provide a positive foolproof closurefor container 20. FIGURE 3 shows flap 32 folded inwardly first, followedby flaps 30 and 31 (FIGURE 4) and finally (FIGURE 5) outer flap 33 isfolded inwardly showing the outer trapezoidal extension being insertedin slot 40.

Another way of folding the various extension flaps to reclose container26 would be to fold flap 30 in position first, followed in succession byflaps 32, 31, and finally with flap 33. Similarly flap 31 may be foldedin position first followed by fiaps 32, 30, and 33 in the order stated.

Still another way of reclosing the top wall of container 20 is to foldflaps 3t and 31 in position followed by flap 32 and then outer flap 33.

From the unique construction of the flaps 31, 32, 33, and 34 and theircooperation irrespective of the way in which they are sequentiallyoverlapped to form top 26, it will be apparent that a foolproof closureis provided which provides a positive locking closure for container 20.

Sealing flap 43 keeps outer flap 33 in position and top 26 closed priorto initially opening container 20. Flap 43 is fastened to container 29by suitable fastening means, for example glue or the like, associatingonly with flap 43. Upon tearing off sealing flap 43 the remaining flapsprovide the positive locking closure as previously described.

While in the exemplary embodiment of the invention the sealing strip 43is integral with flap 33 prior to being torn 01f, it will be appreciatedthat a container could be provided in which the sealing flap isseparate.

Container 20 can be made in any suitable manner and made from anysuitable foldable material. Itis preferably formed from the containerblank 50, illustrated in FIGURE 7. Blank 50 is made of cardboard or thelike having a side such as the exposed surface thereof laminated withmetallic foil, such as aluminum-containing metallic foil, or the like,suitably colored, embossed, imprinted or remaining plain as desired.

Blank 50, in this example, is suitably cut and scored to define sixfoldably connected walls shown as walls 21, 22, 23, 24, 25, and 26.Walls 23, 21, 24, and 22 are defined and foldably interconnected by aseries of parallel score lines 52, 53, 54 and 55.

Score means shown as score lines 34, 35, 36, and 41 in blank 50 defineextension flaps 30, 31, 32, and 33, extending from walls 21, 22, 23, and24 respectively. Each extension flap 30, 31, 32, and 33 is foldableabout its base which is the same width as its associated wall andcoincides with score lines 34, 35, 36, and 41 respectively.

Suitable cut and/or score means is provided in each extension flapdefining its specific structural configuration as will be subsequentlydescribed, such configuration providing locking means. It will be seenthat irrespective of the sequence of closing each extension flap uponassembling container 20 from blank 50, the top 26 of container 20 formedby such extension flaps is positively closed upon finally closing outerflap 33.

The foolproof locking closure for reclosing container 20 is providedafter tearing away the sealing strip portion 43.

Walls 21 and 22 are designated as end walls in the assembled containerhaving extension flaps 30 and 31 as previously mentioned. Extension flap3% has its base'defined by score line 34 and its area defined by arectangular portion 30A and a right triangular portion 308 lying withone of their sides along score line 34 and another of their sidesadjoining. One side of rectangular portion 30A is defined by slit line56 in blank 50'. The right triangular portion has its hypotenuseextending between one ter minal end of the extension flap base definedby fold line 34 and a point illustrated at 38 along the middle portionof a side of the rectangular portion 30A, which side coincides with theadjoining side. Similarly extension flap 31 has an area defined by asimilar corresponding rectangular portion 31A and triangular portion 31Bhaving one side along score line 35. One side of rectangular portion 31Ais defined by a slit line 57 in blank 50 simi lar to slit line 56. Thehypotenuse of portion 31B extends between a corresponding terminal endof score line 35 and point 39. It will be seen, therefore, that theremaining terminal end of each end wall extension flap 30 and 31 isgenerally rectangular in shape.

Score means defined as a score line 36 is provided in side wall 23defining extension flap 32 coextensive therewith and extendingtherebeyond. Extension flap 32 has its base coinciding with score line36.

A generally U-shaped cut 58 in the terminal end of extension flap 32defines a rectangular cut-out therein and shown at 37. U-shaped cut 58is dimensioned to assure proper cooperation with associated extensionflaps. The outward extension of fiap 32 from its base 36 to its centralouter edge defined by the center portion of U- shaped cut 58 is smallerthan the height of each triangular portion 30B and 318 normal to itsrespective adjoining side.

The dimensioning and structural arrangement thus described assures thatupon forming container 20 and folding flap 32 and flaps 30 and 31inwardly to form a portion of top 26 an elongated slot 40 is definedhaving a width defined by cooperating flaps 30, 31, and 32 and a generallength defined by the central portion of the U- shaped cut.

Score means defined as a score line 41 is provided at the upper end ofside wall 24 and along with slit lines 56 and 57 define the innerportion of a generally rectangular extension flap coextensive therewithand extending beyond score line 41. The base of extension flap 33coincides with score line 41 along its full length.

Cut means shown as slit line 42 having side slits 42A and 42B isprovided in flap 33 defining a generally rectangular tear-off sealingstrip portion 43 coextensive in width with the outer flap 33. Sealingstrip 43 has a generally centrally located cut-out in one side thereofdefined by slit line 42 and having the general shape of a trapezoid. Thecut-out is centrally arranged along one edge of strip 43 with its widerparallel side thereof coinciding with the tear edge illustrated at 42Aand 4213 at opposite sides of strip 43. It will be seen that upontearing ofi? tear-off strip 43 a centrally located trapezoidal extensiontongue 45 is provided at the terminal end of extension flap 33.

Upon assembling container 20 from blank 55 sealing strip 43 is torn awayto open such container and the outer flap 33 assures, upon being finallyclosed, that irrespective of the inward folding sequence of the end walland side wall extension flaps that the trapezoidal extension 45 will beinserted in the slot 40 to positively lock and close container 20.

Flap 33 has a pair of triangular portions 47 and 48 defined by scorelines 47A and 48A respectively in the outer corners of the rectangularportion of the outer flap 33. Such triangular portions assure that top26 of container 20 is positively closed.

Score lines 47A and 48A in flap 33 lie along lines defined by extendingeach nonparallel side of the trapezoidal extension 45 inwardly towardthe end of the base of extension flap 33, which is defined by fold line41, which is adjacent thereto.

Blank 50 has a closing tab 60 at one end thereof extending beyond scoreline 52. Score line 52 also defines one side of side wall 23 aspreviously mentioned.

In addition, as particularly illustrated in FIGURE 7, each wall 21, 22,23, and 24 has a bottom forming flap at its opposite end defined byscore lines 61, 62, 63, and 64 respectively in each wall and a series ofparallel slits 6 65, 66, and 67 in blank 5! The bottom flaps cooperateto define the bottom 25 of the container 20 once blank 50 is folded toform a container. Closing tab 60' is fastened to side wall 22 along oneof its sides by any suitable means such as glue or the like.

The terms bottom, or top wall, top, end wall, and side wall have beenutilized in this description and the appended claims merely to definethe position of the walls as shown in the drawings. It is to beunderstood, however, that the container as shown could be oriented inany manner.

Thus, it is seen that an inexpensive foolproof locking closure isprovided for reclosing a container top after initially opening such topby tearing away a portion thereof which is integral with one of aplurality of extension fiaps which fold into a common plane to definesuch top. It will be seen that irrespective of the order of folding suchextension flaps a positive locking closure is provided. Further, thisinvention provides an improved container blank for forming suchcontainer and closure or the like.

While the form of the invention now preferred has been disclosed asrequired by the statutes, other forms may be used, all coming within thescope of the claims which follow.

What is claimed is:

1. A foolproof locking closure for reclosing a container after openingan exterior wall thereof comprising side wall means, extension flapmeans including an outer flap extending from said side wall means, atear-off portion in the terminal end of said outer flap cooperating withsaid extension flap means to initially keep said container closed, saidextension flap means cooperating with the remaining portion of saidouter flap to close said exterior wall after the initial openingthereof, and locking means in said extension flap means cooperating withsaid outer flap such that irrespective of the sequence of closing saidflap means a positive closure is provided for said container uponfinally closing said outer flap.

2. A container locking closure as set forth in claim 1 includingfastening means provided for association only with said tear-off portionto keep said container closed initially.

3. A foolproof locking closure for reclosing a container after openingan exterior wall thereof comprising, a plurality of side walls,extension flap means extending from said side walls and cooperating toclose said exterior wall, with one of said extension flap means definingan outer extension flap, a tear-0i portion in the terminal end of saidouter flap cooperating initially with said extension flap means toinitially keep said container closed, said extension fiap meanscooperating with the remaining portion of said outer flap to close saidexterior wall after the initial opening thereof, and locking means insaid exten sion fiap means cooperating with said outer flap such thatirrespective of the sequence of closing said flap means a positiveclosure is provided for said container upon finally closing said outerflap.

4. A container locking closure as set forth in claim 3 comprising, cutmeans in said outer extension fiap defining said tear-off portion, saidtear-off portion being of generally rectangular configuration andcoextensive in width with said outer flap and having a generallycentrally located trapezoidal cut-out in one side thereof with the widerparallel side of said trapezoidal cut-out coinciding with the tear edgeof said rectangular tear-off portion, and fastening means provided forassociation only with said tear-off portion to keep said containerclosed initially.

5. A foolproof locking closure for reclosing a container top comprising,a pair of oppositely arranged end walls, an extension flap extendingfrom each end wall and each having its base of the same width as itsassociated end Wall and having an area defined by a rectangular and aright triangular portion each lying with one of their sides adjoining,said triangular portion having its hypotetop.

nuse extendingbetween one terminal end of said base'and a point alongsaid adjoining side, first and second oppositely arranged side walls, anextension flap in said first side Wall having-its base the same width assaid first side wall and having a rectangular cut-out at it terminal enddefined by a U-shaped cut therein, said extension flaps being adaptedfor folding inwardly to define centrally located elongated slit means, agenerally rectangular extension flap in said second side wall having itsbase coextensive therewith and defining an outer extension flap, and cutmeans in said outer extension flap defining a generally rectangulartear-otf portion coextensive in'width with said outer flap and having agenerally centrally located trapezoidal cut-out in one side thereof withthe wider parallel side of said trapezoidal cut-out coinciding with thetear edge of said rectangular tear-off portion, such that upon tearingoff said tear-off portion a centrally located trapezoidal extension isprovided at the terminal end of said rectangular outer extension flap,said outer flap assuring upon being finally closed that irrespective ofthe inward folding sequence of said end wall and first sidewall-extension flaps said trapezoidal extension is inserted in said slitmeans to reclose said container and the outer corners of saidrectangular portion of said outer flap assure positive locking for saidtop.

6. A container locking closure as set forth in'claim includingfasteningmeans provided for association with said tear-off portion to keep saidcontainer closed initially.

7. A container locking closure as set forth in claim 5 in which saidouter fiap further comprises symmetrically arranged score means in therectangular portion thereof along lines defined by extending eachnon-parallel side of said trapezoidal extension to the end of said outerextension flap base adjacent thereto, said score means providing greaterflexibility for said outer flap during insertion of said trapezoidalextension in said slit means, and identification means on the outersurface of said outer flap assuring that it will be the final one to befolded to close said 8. A foolproof locking closure for reclosing acontainer top, said container being made from a singlesheet of foldablematerial comprising, a pair of oppositely arranged end walls, anextension flap extending from each end wall and each having its base ofthe same width as its associated end wall and having an area defined bya rectangular and a right triangular portion each lying with one oftheir sides adjoining, said triangular portion having its hypotenuseextending between one terminal end of said base and a point along saidadjoining side, first and second oppositely arranged side Walls, anextension flap in said first side wall having its base the same width assaid first side wall and having a U-shaped cut in its terminal enddefining a generally rectangular cut-out, said extension flaps beingadapted for folding inwardly to define centrally located elongate-d slitmeans, a generally rectangular extension flap in said second side Wallhaving its base coextensive therewith and defining an outer extensionfiap, cut means in said outer extension flap defining a generallyrectangular tear-off sealing flap portion coextensive in width with saidouter flap and having a generally centrally located trapezoidal cut-outin one side thereof with the wider parallel side of said trapezoidalcut-out coinciding with the tear edge of said sealing flap, such thatupon tearing off said sealing flap a centrally located trapezoidalextension tongue is provided at the terminal end of said rectangularouter extension flap, symmetrically arranged score means in said outerflap, and fastening means provided for association with said tear-offsealing flap portion to keep said container closed initially, wherebyupon tearing away said sealing flap the remaining portion of said outerflap assures, upon being finally closed, that irrespective of the inwardfolding sequence of said end wall and first side wall extension flapssaid trapezoidal extension is inserted in said slit means to reclosesaid container and the outer corners of saidv rect-angular portion ofsaid outer wall assurepositive looking for said top while said scoremeans provide flexibility, for easy insertion in said slit means.

9. A container blank being cut and scored to define a container having atop which is initially opened by tearing away a portion thereof andwhich has a foolproof locking closure for reclosing said top, said blankdefining six foldably connected exterior Walls including a pair of endwalls and first and second side Walls, score means in each end walldefining an extension flap therebeyond each extension flap having itsbase coinciding with said score means and of the same width as itsassociated end wall and having an area defined by a rectangular and aright triangular portion lying with one of their sides adjoining,

said right triangular portion having its hypotenuse extending betweenone terminal end of said base and a point along the middle portion of aside ofsaid rectangular portion which coincides with said adjoining sidesuch that the terminal end of each end wall extension flap is gen--erally rectangular, score means in said first side wall defining anextension flap coextensive therewith and extending therebeyond andhaving its base coinciding with said first side wall score means, agenerally U-shaped cut in the terminal end of said'first side wallextension flap defining a rectangular cut-out at its terminal end, saidextension flaps being adapted for folding inwardly to define centrallylocate-d elongated slit means, score means in said second side walldefining a generally rectangular extension flap coextensive therewithand extending therebeyond and having its base coinciding with saidsecond side wall score means, and cut means in said outer extension flapdefining a generally rectangular tear-off sealing strip portioncoextensive in width with said outer flap and having a generallycentrally located trapezoidal cut-out in one side thereof, with thewider parallel side of said trapezoidal cut-out coinciding with the tearedge of said rectangular tear-off portion, such that upon tearing offsaid tearoif portion a centrally located trapezoidal extension tonguetongue is provided at the terminal end of said rectangular outerextension flap, whereby upon assembling said container from said blanksaid sealing strip is torn away to open said container top and saidouter flap assures upon being finally closed that irrespective of theinward folding sequence of said end wall and first side wall extensionflaps said trapezoidal extension is inserted in said slit means toreclose said container and the outer corners of said rectangular portionof said outer flap assure positive locking for said top. 7

10. A container blank is set forth in claim 9 in which said outer fiapincludes symmetrically arranged score means in the outer rectangularportion thereof along lines defined by extending each nonparallel sideof said trapezoidal extension to the end of the base of said outerextension flap adjacent thereto.

11. A container having a foolproof locking closure defining its top wallmeans comprising, a pair of oppositely arranged end walls, an extensionflap extending. from each end wall, first and second oppositely arrangedside walls, a first approximately U-shaped extension flap extending fromsaid first side wall and having a base portion and a pair of identicaloutwardly extending leg portions, said first extension flap beingfoldable inwardly with said extension fiaps extending from saidend wallsto define top wall means having substantially centrally locatedelongated slit means provided therein and said first extension" havingan area defined by a generally trapezoidal central portion flanked by apair of substantially identical right triangular tab portions eachhaving a height less than the height of said trapezoidaltportionto thusdefine a trape-' zoidal extension arranged outwardly of said righttriangular tab portions, and eachtof said right triangular tab' portionshas a base portion which partially overlaps an associated one of saidleg portions to provide a positive locking of said top wall means uponfinally folding said outer extension flap in position and inserting saidtrape zoidal extension in said slit means irrespective of the priorfolding sequence of said end wall and first side wall extension flaps.

12. A container closure as set forth in claim 11 in which said outerextension flap further comprises symmetrically arranged score meanstherein defining the hypotenuse of each of said triangular tab portionsto provide greater flexibility therefor and assure easier cooperationwith said extension flaps arranged therebeneath to provide said positiveclosure for said container.

13. A container blank being cut and scored and adapted to be assembledtogether to define a resulting container having an integral foolprooflocking closure defining its top wall means, said blank comprising, apair of end walls adapted to be oppositely arranged in said resultingcontainer, an extension flap extending from each of said end walls,first and second side Walls adapted to be oppositely arranged in saidresulting container, a first approximately U-sl1aped extension flapextending from said first side wall and having a base portion and a pairof identical outwardly extending leg portions, said first extension flapbeing adapted to be folded inwardly with said extension flaps extendingfrom said end walls in said resulting carton to define top wall meanshaving substantially centrally located elongated slit means providedtherein and said first extension flap having said leg portions arrangedadjacent opposite ends of said slit means and extending therebeyondtoward said second side wall,

and an outer extension flap extending from said second side wall, saidouter extension flap having an area defined by a generally trapezoidalcentral portion flanked by a pair of substantially identical righttriangular tab portions each having a height less than the height ofsaid trapezoidal portion to thus define a trapezoidal extension arrangedoutwardly of said right triangular tab portions, and each of said righttriangular tab portions has a base portion which in said resultingcontainer partially overlaps an associated one of said leg portions toassure apositive locking of said top wall means upon finally foldingsaid outer extension flap of said resulting container in position andinserting said trapezoidal extension in said slit means irrespective ofthe prior folding sequence of said end wall and first side wallextension flaps.

References Cited UNITED STATES PATENTS 2,034,594 3/1936 Norris et a1229--39 2,186,109 1/1940 Hultin 22951 2,390,412 12/ 1945 Axsherg 229-512,661,143 1/1953 Inman 229-37 2,685,400 8/ 1954 MacArthur [229-513,258,192 6/1966 Kelty 22939 FOREIGN PATENTS 449,968 7/ 1936 GreatBritain. 714,683 9/1954 Great Britain.

DAVIS T. MOORHEAD, Primary Examiner.

